Micromechanical components are equipped with a cap for special application purposes or just in order to protect them. Glass frit bonding or anodic bonding, inter alia, are conventional for fastening a cap on the component. European Patent No. EP 1 274 648 B1 describes a packaging using thin layers, a so-called SMM encapsulation (SMM—surface micromechanics). The basis of this technology is a perforated layer made of epitaxial polysilicon over a cavity that contains a micromechanical functional element. The perforations allow the cavity to be accessed from the outside during the manufacture of the micromechanical component.
Conventional semiconductor technologies (e.g., oxide or nitride depositions) are described as cap closure, which, however, impose severe boundary conditions on the actual functional element. In this connection, vacuum methods are used and thus also correspondingly low pressures inside the component. In this instance, the composition of the atmosphere in the interior naturally plays only a secondary role.